Hi,
unfortunately, at the moment, we don’t have any tool to do this automatically or in the best way.
I can suggest a workaround: use a plugin that exports the products of your website and then import into the product catalog on your business manager account. You’ll need to select the right fields in the business manager in order to have the products feed imported correctly.
If you are using WooCommerce as plugin for eCommerce, I can suggest the plugin Product Import Export for WooCommerce. This lets you also to select the fields you want to export and name them specifically, so you can work according facebook wants the data.
In case you are not using WooCommerce, you can search for a plugin that gives you ability to export the products in the plugin format or in alternative use the WordPress export tool from WP Admin -> Tools -> Export.
I hope it can helps you ??
